Tooth



W. F. SLACK.

ARTIFICIAL TOOTH.

APPLICATION FILED FEB. 24. I919.

' 1,312,141. Patented Aug. 5,1919.

4 6 a:z:mmmxmmmmm\mummw I Al%rny a the toothis composed and that oftheanchor.

WILLIE r. SLACK, orivmnonnsrnn, NEW niuvrrsi-nnn,

ARTIFICIAL ro m.

' ...s ecifieation ortettersratent. f Patented Aug. 5, 1919.1

' Application iiled alar e4, 1919; SeriaINo. 275,671;

To all whom Mandi concern."

Be it known that LVILLIEFI SLACK, a

citizen of the United States, and a resident of Manchester c State ofNew Hampshhe, have invented an Improvement in Artificial Teeth, ofwhich.

the following description, in connection with the accompanying drawngs,1s a spec1fication, like characters on the drawings repre sentinglike parts.

The invent on to be hereinafter described rlelatesto an lmprovement inartificial teeth and more particularly tothemeans for at taching suchteeth to a plate,such as rubber,

celluloid, or othersuitable character.

lHeretofore it has been the common practice to form artificial teeth ofasuitable composition such, for instance, as porcelain, and to provide ananchorage betweenthe teeth and the plate to which the teeth are to besecured, such anchorage usually comprising a platinum pin. When the,artificialjteeth have been heretofore subjected to the firingjoperation, the platinum pin or anchor has been embedded in the porcelaintooth and as the tooth cooled after the firing operation,

the coefficient of contraction or,converse ly, of expansion between thesubstance of whlch has been such as to cause or platinum pin, This isdue to the the porcelain to crack.

fact that as the porcelain contracts about the embedded platinum pin,its contraction, is; g impeded by the less contractibility of the,

pin itself as the parts cool. Under these circumstances something mustgive way and this has been usually the material or porcelain of whichthe tooth iscomposed. The crack usually extends transversely of thelingual or labial surface, although this is not always the case. Thecrack thus formed or the line of weakness thus produced, is

usually not visible to the naked eye, but it; an extent that after theteeth exists to such have been secured to the plate and are subjected tothe usual strains incident totheir use, the teeth are found to give wayor break along the line of weakness produced by the differentialcontraction of the material of the tooth and that of the pin or anchor.

One of the objects. of the present inven tion is to provide anartificial tooth with an anchor which will not interfere with theuniform contraction of the material of the tooth as the tooth is cooledafter the firing process, and will permit such relative conounty ofHillsborough, and

. traction between thematerial of the tooth and the plnor anchor,as toobviate the for mation of a line ofweakness or crack in the tooth. j

Another feature of the present invention cons sts in: providing anartificial tooth with an anchor or pin of such character that it willeffectively hold the tooth to the plate into which the anchor projects.In carrying the invention into practical effect, the anchor or pin isusually and preferably formed ofa metalrod of suitable size provided onits exterior surface with barbs or projections which may be producedmost readily in the form of screw threads When such form of anchor isembedded in the porcelain of the tooth when theflatter is shrunk orcontracted during cooling,ma nifestly the pin becomes securedpermanently and uniformly throughout the embedded portion thereof in thematerial of the tooth.

In order to permit the differential expan sion ofthe material of thetooth or porcelain and that of the anchor or pin, the pin; is

provided with a slot in the end thereof which projects into the materialof the tooth,

uch slot permitting movement of the two or more parts of the pin towardor from eaclrother due to the contraction and expanslon of thematerialof the tooth. f I have found excellent resultsto follow from providingthe pin with a single slot extending from the embedded end portion ofthe pin toward the inner portion ofthe tooth, but, obviously, the pinmay be provided with more than a single slot and in some cases suchduplication or multiplication of slots may be desirable.

In thedrawing; X l c t Figure 1 isa section view .onan enlarged scaleshow ng an artificial tooth securedto,

the backing. or plate in accordance with the present invention; s

Fig.2 is a perspective view showing in general outline the artificialtooth with the anchors or pins embedded therein;

Fig. 3 is a view of a slightly modified form of anchor or pin and itsrelation to the artificial tooth;

Fig. 4 is an enlarged view representing one of the pins in Fig. 4, theenlargement being multlplied many times in order to make clear thecharacteristic features thereof.

In the drawings, the artificial tooth 1 may be formed of any suitablesubstance such,

for instance, as porcelain, and theplate 2 to which the artificial toothis to be secured, may be likewise formed of any suitable ma terial, suchas rubber, celluloid, or the like.

In order to secure the tooth to the plate, an anchor or pin 3 isprovided with a roughcried" exterior surface, preferably formed as screwthreads 4, although, as will be evident,

the roughened characteristic of the outer surface of the anchor. or pin3 may be other wise produced. It ispreferable to form the anchor or pinwith the roughened or threaded' surface throughout its length forthereacient of expansion and contraction of the substance of the toothand the substance of the pin or anchor differ, and heretofore the 7result has been that a crack either visible 7 or invisible has usuallyextended across or transverse to the lingual surface of the tooth whicheventually permits the tooth to collapse or break duringuse. Toeffectually overcome this defective condition of the artificial toothwhen secured to its anchor or pin, lhave found that by slotting the pin,preferably throughout the portion embedded in the tooth, the substanceof the latter, in cooling, "may contract by more or less closing theslot of the anchor or pin and thereby prevent the formation of visibleor invisible cracks. i

In the present instance of the invention, the anchor or pin is providedwith a slot 5 preferably extending from the end6 of the pin toa point 7longitudinally of the anchor or pin and approximately or. preferablythroughout the portion of the pin embedded inthema'terial of theartificial tooth, as indicated in Fig. 1. 7 j When the anchor or pin 3,slotted as described, is placed in the material of the tooth while theylatter isin plastic or'semi-plastie condition, the slot 5, muchmagnifiedin the copies of this patent may be obtained for five centseach, by

permit contraction of the drawings, receives little or none of theplastic material of the tooth, the consequence being that when thematerial of the tooth is cooled after firing, the slot 5 furnishes asufficient yield between the pin and the material of the tooth duringcontraction to permit full contraction of the latter without rupture orthe formation of visible or invisible cracks.

While the single slot 5 has been indicated in the pin 3 it will, ofcourse, be understood that several such slots may be provided at angularrelation to each other and extend longitudinally of the anchor or pin.

In some casesa single anchor or pin 3 will be quite sufiicient, in viewof the roughened exterior surface thereof, to hold an artificial toothto its backing or plate, but in some instances two or even more may beemployed, as indicated in Fig. 2.

The anchor or pin may take various forms, as indicated in Fig. 3 wherethe anchor or pin 8 is formed substantially U-shape, its end portions 9being embedded in the substance of the artificial tooth 1 and each ofsaid end portions being provided with the longitudinal slot androughened exterior surface, substantially as described hereinbefore.

Claims:

1; An artificial tooth provided with an anchor or keeper comprising apin having one end embedded in the material of the tooth and providedwith a slot extending longitudinally of the anchor or keeper to tooth asit is cooled.

2. An artificial tooth having an anchor or pin embedded therein andprovided with a longitudinal recess extending throughout the portion ofthe pin embedded in the artificial tooth to permit uniform contractionof the tooth in cooling, and having a roughened or tooth surfaceextending transversely to the general longitudinal dimension of theanchor or pin and about the longitudinally recessedor slotted portion.

In testimony whereof, I have signed my name to this specification.

WILLIE F. snac addressing the Commissioner 01' Patents,

Washington, I). 0.

